Machinery which operates in a manner similar to human behavior by electrical or magnetic operation is referred to as a “robot”. The etymology of the word robot is “ROBOTA (slave machine)” in Slavic. In Japan, robots became widely used in the end of the 1960s. Many of these robots are industrial robots, such as manipulators and transfer robots, designed automation and for unmanned production in factories.
Recently, research and development of the structure of legged mobile robots, including pet robots emulating the physical mechanism and the operation of quadripedal walking animals, such as dogs, cats, and bear cubs, and “human-shaped” or “human type” robots (humanoid robots) which emulate the physical mechanism and the operation of bipedal orthograde animals, such as human beings and monkeys, and stable walking control thereof have advanced. There is a growing expectation for practical applications. Although these legged mobile robots are unstable and posture control and walking control thereof are difficult compared with crawling-type robots, the legged mobile robots are superior in that they can walk and run flexibly, such as climbing up and down stairs and jumping over obstacles.
Stationary robots, such as arm robots, which are installed and used at a specific location, operate only in a fixed, local work space where they assemble and select parts. In contrast, the work space for mobile robots is limitless. Mobile robots move along a predetermined path or move freely. The mobile robots can perform, in place of human beings, predetermined or arbitrary human operations and can offer various services replacing human beings, dogs, or other living things.
One use of the legged mobile robots is to replace human beings in executing various difficult tasks in industrial and production activities. For example, the legged mobile robots can replace human beings in doing dangerous and difficult tasks, such as the maintenance of nuclear power generation plants and thermal power plants, the transfer and assembly of parts at production factories, cleaning skyscrapers, and rescue from fires.
Rather than supporting human beings in executing the foregoing tasks, another use of the legged mobile robots is to “live together” with human beings or to “entertain” human beings. This type of robot emulates the operation mechanism of a legged walking animal which has a relatively high intelligence, such as a human being, a dog, or a bear cub (pet), and the rich emotional expressions thereof. Instead of accurately executing operation patterns which are input in advance, this type of robot can make lively responsive expressions which are generated dynamically in accordance with the user's words and mood (“praising”, “scolding”, “hitting”, etc).
In known toys, the relationship between the user operation and the response operation is fixed. The operation of the toy cannot be changed in accordance with the user's preferences. As a result, the user will become bored with a toy which only repeats the same operation.
In contrast, an intelligent robot has an action model and a learning model which depend on the operation thereof. In accordance with input information including external sounds, images, and tactile information, the models are changed, thus determining the operation. Accordingly, autonomous thinking and operation control can be realized. By preparing the robot with an emotion model and an instinct model, autonomous actions based on the robot's emotions and instincts can be exhibited. When the robot has an image input device and a speech input/output device, the robot can perform image recognition processing and speech recognition processing. Accordingly, the robot can perform realistic communication with a human being at a higher level of intelligence.
By changing the model in response to detection of an external stimulus including a user operation, that is, by adding a “learning model” having a learning effect, an action sequence which is not boring to the user or which is in accordance with each user's preferences can be performed.
Even without direct command input from an operator, a so-called autonomous robot can autonomously form an action plan taking into consideration external factors input by various sensors, such as a camera, a loudspeaker, and a touch sensor, and can perform the action plan through various mechanical output forms, such as the operation of limbs, speech output, etc.
When the action sequence is changed in accordance with the external factors, the robot takes an action which is surprising to and unexpected by the user. Thus, the user can continue to be together with the robot without getting bored.
While the robot is operating in cooperation with the user or another robot in a work space shared with the user, such as a general domestic space, the robot detects a change in the external factors, such as a change of time, a change of season, or a change in the user's mood and transforms the action sequence. Accordingly, the user can have a stronger affection for the robot.